part of MHC class I peptide loading complex TAP complex cellular_component GO:0042825 transporter associated with antigen presentation A heterodimer composed of the subunits TAP1 and TAP2 (transporter associated with antigen presentation). Functions in the transport of antigenic peptides from the cytosol to the lumen of the endoplasmic reticulum. membrane protein complex endoplasmic reticulum protein-containing complex